Former Yahoo executive Tim Sanders offers these expert e-mail etiquette tips:

• Never say "No." "E-mail is for 'Yes,' 'Maybe,' passing on information or answering a question," says Sanders. "If you're going to say 'No,' pick up the phone."
• Don't be a copycat. Think before you add a name to the "cc" list—especially if that name belongs to your boss. "The person you are sending the e-mail [to] can become rather resentful," says Sanders.
• Calm down first. "Never send an e-mail when you're mad," says Sanders. "Touch your fingers to your eyelids. If they're hot, put the e-mail into the drafts box and revisit [it] once you've calmed down."
• Consider the time. "If you're the boss," says Sanders, "don't send company e-mails throughout the night. If your employees see you working late, they will feel they have to as well."